When Should I Change My Air Conditioner's Air Filter at Home?

February 26, 2015

Want the fast answer? Check out our FAQ on "How often to change the air filter".

Occassionally we’re asked what is the most important thing that Hillsborough area homeowner's can do to secure their air conditioning and heating system between their seasonal tune-ups? Our advice is simple; remember to change the heating and air conditioning air filter. Replacing furnace and return air filters is extremely important to the effectiveness of your HVAC system, in addition to your home's air quality. Studies show that indoor air pollution is in the top five environmental health risks? You probably don’t consider it as you sit and watch TV, but this is the air you breathe day and night. Changing the air filters is not difficult for most Hillsborough homeowners, but there are typically two challenges to actually completing this job:

Knowing just how often to swap out your furnace or air conditioner filter.
Remembering to change air filters when needed.

When To Change Your Air Filters

Most filters have a recommended guideline on the wrapping. It may read "Lasts up to 3 months" or "Change filter every 90 days". Check out the filters at the store and you'll see that some are meant to only last one month, while other manufacturers (like Honeywell) have released media air cleaners with filters meant to be exchanged once every 6-12 months. The industry standard seems to be once every three months for most higher quality filters, but we have a rule of thumb that we tell our friends, and family to go by. If the filter is dirty, change it! A dirty air filter can contribute or cause damage to costly parts, like your compressor, so it's better to change it out more often than not. If you want to follow the manufacturer's recommended limit, we suggest scribbling the date on the filter when you swap it out, and adding a reminder for yourself in your phone or on a calendar. Keep in mind that your filter manufacturer might have a different recommendation from your HVAC system manufacturer.

Deciding how often to change your air filters relies upon several factors:

The type of air filter you are using
The overall air quality of your Hillsborough area home
Pets – Dogs, cats, etc.
Number of people in the home
The level of air pollution and construction around the home

For the common 1"-3" air filters, the OEM specs basically tell you to change them bi-monthly, which is actually a great rule of thumb. However, general guidelines are not applicable to all. If you put up with light to moderate allergies, you might need to upgrade your air filter or change them even more regularly than OEM specifications. On the other hand, if you're in a low population area, own a seldom occupied home (like a vacation home) or an area with few automobiles and trucks, annual replacement of your air filter may be quite sufficient. Why do we call out our beloved pets? They have a tendency to shed, which can clog your air filter fast. Clearly, the air filter is just doing its job by containing pet hair and dander, but extremely dirty filters can cause weak HVAC performance.

In summary:

Seldom used home or single occupant homes without pets or allergies: Change 6-12 months
Common suburban home without pets: Change every 90 days
Got a cat or dog: Change every 60 days
Multiple pets or have allergies: Change every 30-45 days

How To Remember To Change Your Air Conditioner's Air Filters

It's simple; sign up for the Service Experts Email Club. When you do, you can elect to receive (or not) great email coupons and newsletters with a lot of tips and discounts on AC repairs and tune-ups. Also, your email subscription preferences let’s you set a reminder to change your Hillsborough area home's air filter every 30, 60, 90, 120 or 365 days, or the date of your choosing.

How to replace your return air filter

Most people know how to replace the air filter in their system, but some residences have an additional filter in the return ductwork. Whether you have one or not is dependent on what your unit's manufacturer recommends. Your unit is designed to handle a certain amount of pressure in your house, and the more filters you have the harder the blower motor works, which can reduce the lifespan of your system if it isn't designed for it. Discovering whether you have a return filter and replacing it is a piece of cake:

Find your return air vents.
Some covers have screws and some have tabs. Unscrew or pull tabs to remove from the wall.
Look for a filter. If one is inside, pull it out and write down the size.
Verify the filter type is the one recommended by the manufacturer.
If filter is dirty, replace with the manufacturer's recommended filter of the same size and type.

Incredible though it may seem, filters can greatly affect your home's airflow, which is why we recommend referring to the manufacturer. A more expensive HEPA filter that is designed to catch smaller particles will reduce airflow more than a cheaper filter. With restricted airflow comes more pressure on your system, so you ought to verify that your HVAC system was made to handle it. Otherwise, you could experience reduced heating and cooling efficiency in your home, and unit parts may break down much faster than the standard.

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